A nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery is in widespread use as a battery for use in devices such as a personal computer, a mobile phone, and a mobile information terminal. Attention is paid to, in particular, the lithium-ion secondary battery because the lithium-ion secondary battery emits less carbon dioxide and makes a greater contribution to energy saving than a conventional secondary battery.
There has so far been advancement in development of a separator winding core around which a nonaqueous electrolyte secondary battery separator (film) is to be wound (see Patent Literature 1).